This invention relates to machines, such as street sweepers, that move across a surface while sweeping that surface with rotary brushes mounted on disks generally parallel to the ground.
Sweeping machines for streets, factory floors and the like generally include wheel mounted vehicle that moves across a street, floor or other surface to be swept. Most include a brush assembly on each side of the machine, each assembly including a disk on which the brush is mounted with the disk approximately parallel to the surface to be swept and rotatable to sweep dirt and debris from the surface towards a container for disposal.
Conventionally, each brush assembly consists of a heavy metal disk mounted on the sweeping machine for rotation adjacent to the surface to be swept. Brush holders, each a segment of a circle, are bolted to the underside of the disk adjacent to the disk periphery forming a circle. Generally, the brushes are made up of U-shaped bristles formed from stiff metal wire, such as piano wire and are attached to the brush holder.
These bristles tend to wear rapidly, particularly where the surface is rough, such rough concrete surfaces. Therefore, the brush holders must be removed from the disk and the bristles be replaced at regular intervals. To replace the brush holders requires elevation of the support disks and unbolting the brush holders from the support disks. This is a time consuming task which is difficult and can be dangerous because of the great weight of the support disks. The bolts may become jammed, rusted and are supporting the weight of the brush holders and brushes. Reinstallation requires holding the brush holders so that holes in the holders align with corresponding holes in the support disks. This is difficult with the heavy brush holders adjacent to the ground with no means of maintaining alignment during installation.
The brush holders, which are generally formed from a plastic material also wear and suffer cracks and must be replaced quite often. In addition the angle of the bristles to the surface being swept is often other than the optimum sweeping angle.
Thus, there is a continuing need for improved brush assemblies that allow replacement of brush holders and bristles in an easy, rapid and safe manner, that maintain alignment between brush holders and support disks during disassembly and reassembly that provide an optimum sweeping angle between bristles and the surface to be swept and that are resistant to cracking of brush holders in use.
The above-noted problems, and others, are overcome in accordance with this invention by a brush assembly which comprises a circular disk for mounting on a sweeping machine adjacent to a surface to be swept, brush holders for mounting along the periphery of the lower side of the disk and alignment holes in the brush holders for properly aligning the brush holders and a clamping arrangement for clamping the brush holders against the disk.
The brush holders have a number of bristle mounting holes extending from the side in contact with the disk to the opposite side for receiving brush-bristles. The bristles have a narrow U-shape. A transverse retainer wall extends across each mounting hole to hold the bristles, which are installed in the holes with the two legs of the U-shape on opposite sides of the retainer wall.
The clamping arrangement comprises a clamp bar that extends along the surface of each brush holder opposite the side in contact with the circular disk and extends beyond the brush holder towards the center of the disk. The clamp bar is firmly pressed against the disk by at least one threaded member extending through the clamp bar and disk, typically a bolt and nut arrangement or by a stud secured to the plate and extending through the clamp bar to a nut. For best results an offset support is secured to the edge of the bar towards the disk center, with the threaded member between the offset support and the brush holder. The offset support preferably has a thickness approximately equal to the thickness of the brush holder to assure uniform clamping pressure on the brush holder.
In order to assure proper alignment of the brush holder with the circular disk, alignment pins are provided on the clamp par to project into corresponding alignment holes in the brush holder.
For best results, the bristle mounting holes should be angled outwardly of the disk center an angle to the disk of about 60xc2x0 to 65xc2x0, to provide optimum sweeping of debris and dirt. Optimally, this angle has been found to be about 62xc2x0. While any suitable number of bristle mounting holes and hole dimensions may be used, three rows of holes along the disk periphery provides excellent results. Best results are obtained with bristle mounting hole cross sections having widths of from about 0.4 to 0.6 inch and depth of from 0.7 to 1 inch. The overall thickness of the brush holder is preferably from about 0.75 to 1.25 inch, so that length of the bristle mounting holes is correspondingly just greater that 0.75 to 1.25 inch.
In order to prevent cracking of the brush holders at corners of the bristle mounting holes or at any other intersections between flat surfaces, all such corners are preferably rounded. Ideally, the radius of all corners is from about 0.030 to 0.150 inch. We have found that this rounding apparently prevents stress peaks at those corners and will add considerably to the useful life of the brush holders.
While the brush holders may be formed from any suitable material such as aluminum or high strength plastics, for optimum durability together with convenience of manufacture by injection molding, nylon of the sort available from Dupont under the xe2x80x9cNylon 66xe2x80x9d designation is preferred. For further strength, the nylon may be filled with fibers such as short glass fibers.